1. Technical Field of the Invention
The present invention relates to a kit for the withdrawal of a filter for blood vessels.
Two main types of filters for the inferior vena cava are known at present. It should be recalled that a filter for the inferior vena cava is a device consisting of metallic strands resembling the frame of a half-open umbrella but having only the ribs and the bosshead of the latter, which is installed in the inferior vena cava. The metallic strands are provided with hooks at their free end, enabling them to cling to the vessel wall.
2. Prior Art
These metallic strands ore thin and flexible and they therefore beat in rhythm with the peristaltic movements of the inferior vena cava. These movements, which cause the metallic strands to come closer and move away alternately, make it possible, when the umbrella filter blocks a clot, for the latter to be sheared progressively into small pieces that can no longer be harmful.
The first type of filter is the permanent type; in this case an umbrella filter is installed above in the inferior vena cava, and is left there permanently. The medical profession is always reluctant to leave a foreign body in the human body permanently.
Temporary filters are also known. In this case a filter is fitted to the end of a catheter which is left in place and is withdrawn when the time comes. However, the catheter can cause adhesions, which tear the vessel wall on withdrawal. Furthermore, being about fifty centimeters long, the catheter must remain partially outside of the body, and so is a source of infection. That is why patients fitted with a temporary device are maintained under strict hygiene and receive permanent antibiotic-based medication.